The present invention relates to an electrodeless light source excited by power in the microwave region of the electromagnetic spectrum.
In view of the necessity of conserving natural resources, much effort has recently been directed to research in electrodeless light sources. An electrodeless light source requires less electrical power than the conventional incandescent light source which in turn reduces the demand for fossil fuels for power generating facilities.
An electrodeless light source is described in the U.S. patent to Haugsjaa et al., No. 3,943,403 which is assigned to the same assignee as the present invention. This light source includes a source of power at a high frequency, such as in the range of 10 MHz to 300 GHz, and an electrodeless lamp having an envelope made of a light-transmitting material and a volatile fill material within the envelope. The fill material emits light upon breakdown and excitation. A termination fixture is coupled between the source and the lamp and has an inner conductor and an outer conductor disposed around the inner conductor, one pair of ends of the conductors being coupled to the lamp while the other pair is coupled to the source. The fixture has the capability of matching the impedance of the lamp during the state of excitation to the output impedance of the source to optimize the coupling of microwave power to the lamp. Lamps according to this arrangement have been operated with light outputs substantially greater than that of the conventional incandescent lamp for the same input electrical power. While an electrodeless light source according to the teachings of this patent has operated satisfactorily, there exists a need to further improve the efficacy of such light sources.